The Start of Work on a Unique Pair of Tunnels in Wales

September 10, 1962

Construction began on twin tunnels in the city and unitary authority area of Newport in southern Wales. These tunnels were built to carry M4 of the United Kingdom (UK) motorway network under Brynglas Hill in that region of Wales. Sir Owen Williams, the prolific English engineer and architect, was in charge of the project.

The Brynglas Tunnels were opened to traffic in May 1967. These structures, measuring 390 yards (360 meters) in length, remain the only twin-bored tunnels that are officially classified as part of the UK motorway network. (While the twin-bored tunnels known as the Dartford-Thurrock River Crossing in southern England are located on the route for M25, they are technically not considered to be part of that motorway.)

In discussing the heavily used tunnels in a 2017 interview with BBC News, veteran Welsh government engineer Brian Hawker readily acknowledged that they have become a major bottleneck on M 4. He also emphasized the positive side of the Brynglas Tunnels’ legacy, however. “The tunnels are not only of historical importance to Wales, they opened up social opportunities that we struggle to comprehend today,” said Hawker. “When you’re stuck in a traffic jam, you don’t tend to appreciate the historic significance of the tunnel you are sitting in. It is an engineering marvel and helped the economic and social well-being of south Wales overnight.”

Photo Credit: John Thorn (licensed under the Creative Commons Attribution Share-Alike License 2.0)

For more information on the Brynglas Tunnels, please check out

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create a website or blog at

Up ↑

%d bloggers like this: